Background: We previsously reported results of a randomized phase III trial comparing androgen-deprivation therapy (ADT) combined with external beam radiation therapy (EBRT) and ADT alone in patients treated with localized cancer. We report here long-term oncological outcomes of this trial. Methods: In this multicenter phase III trial, patients with biopsy-proven locally advanced prostate cancer (T3-4) randomly assigned to ADT alone or ADT+EBRT. In both arms, leuprorelin 11.25 mg, subcutaneous, was started within seven days of randomization and continued every three months for three years and oral flutamide (750 mg/day) was administered during the first month. For the ADT-EBRT arm, the whole pelvis was treated at a dose of 46+/-2 Gy and the prostate with a boost from 20 Gy to 28 Gy. Primary endpoint was progression-free Survival (PFS) which included biochemical and clinical events and deaths. Secondary endpoints included overall survival (OS), disease-specific survival (DSS), locoregional progression free survival (LPFS), metastasis-free survival (MFS), biochemical progression free survival (BPFS) and tolerance. Competing-risk analysis was used whenever appropriate. Results: With a median follow-up of 7.3 years, 263 patients were included in the Intent-to-treat analyses. The 8-year PFS rate was significantly higher in the ADT+EBRT arm than in the ADT arm (47.9% versus 7.0%; hazard ratio: 0.27, p < 0.0001). The risk of death from prostate cancer was significantly reduced for ADT+EBRT arm as compared to ADT alone (sub-hazard ratio (SHR): 0.48; p = 0.02). The 8-year OS rate was respectively 56.8% in the ADT arm and 65.1% in the ADT+EBRT arm (p = 0.43). LPFS was significantly in favor of ADT+EBRT arm (SHR = 0.61; p = 0.01). MFS was comparable between both arms (p = 0.88). Analysis of toxicities revealed acute lower tolerance (mainly gastro-intestinal and genito-urinary) in the ADT+EBRT arm with a gradual decrease in intensity during follow up from 6 months after the end of EBRT. Conclusions: These long-term results confirm the oncological benefit of combining EBRT with ADT in the treatment of locally advanced prostate cancer. Clinical trial information: NCT01122121